1. Field of the Invention
This invention relates in general to ordinance and ammunition, and more particularly to a projectile for firing from a smooth bore gun tube, with means for utilizing a portion of the gun propellant gas to produce a spin on the projectile.
2. Description of the Prior Art
It is generally well known that projectiles fired from smooth bore gun tubes are prone to dispersion due to dissymmetry in the construction of the projectile, and particularly to misalignment of the stabilizing fins. Conventionally, the effects of fin misalignment and the like are compensated for by canting or beveling the leading edges of the stabilizing fins. The canted or beveled fins impart a torque to the projectile which causes it to spin about its longitudinal axis during flight, thus averaging out any fin errors.
A major problem with canted or beveled fins, however, is that they do not produce a constant spin rate, but rather a spin acceleration which is proportional to the angle of the cant or bevel. Thus, fins with small cant or bevel angles do not impart a high enough spin rate until relatively late in the projectile's flight, at which point significant dispersion may have already occurred. On the other hand, fins with large cant or bevel angles cause the projectile to spin at the desired rate early in flight, but at excessively high spin rates later on. In certain types of projectiles, such as in armor penetrating ammunition utilizing shaped charge warheads, threse excessive spin rates are undesirable because they tend to degrade the performance of the warhead and may result in additional dispersion due to spin-yaw resonance.
Accordingly, a need exists for a new and improved projectile for firing from a smooth bore gun tube, with means for quickly spinning the projectile to its optimum spin rate.